In transscleral drug delivery method, drug is entered in the periocular space of the eye, precisely against the outer region of the sclera. Transscleral drug delivery is considered as a promising route of ocular drug delivery due to the large surface area of the sclera (which is approximately 16.3 cm2), its porosity and fewer enzymatic activities to degrade drug, compared to the cornea. Despite all these advantages, some obstacles adversely affect the efficiency of transscleral route, such as orbital clearance, intraocular pressure, uveoscleral outflow, choroidal blood flow, and the blood-retinal barriers. Currently, one of the main obstacles of the transscleral drug delivery is the drug removal by inevitable bulk fluid flow in the back of the eye, and an eventual clearance by vasculature of conjunctive or choroid.
Hence, there is a need in the art for a transscleral drug delivery method to reduce the orbital clearance of drugs, which are administered transsclerally for the treatment of the diseases of the eye.